Patrick
I have a question for the laboratory specialists on this forum: Can water that has been treated by a water softener have a negative effect on film and paper development?
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As this softening process replaces calcium particles with sodium, I wonder whether this slightly increased sodium content in the water might have an effect (the rule here is that the harder the water, the more sodium remains in the water after treatment, as more calcium particles had to be replaced – and our water is quite hard).
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I always thought the softer the water, the better, because then fewer limescale marks appear on the dry negatives. I was really looking forward to installing our new system. Recently, however, I read in the book "Photographic Possibilities" by Robert Hirsch and John Valentino that water that is too soft can affect the stability of the developer...
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I’d be interested to hear about your experiences with softened water.
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Best regards to all, Patrick.
AchimBauer
Hello Patrik,
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Unfortunately, I don’t have any laboratory experience with softened water!
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But I do have experience with softened water in other contexts, including as potting water, where it can damage soil. And at work, a technician told me that they can only run the water (desalinated, mixed with tap water to 4.5°) through plastic pipes because it would corrode metal.
I find the whole thing extremely suspicious.
I have very hard water at home and no problems in the lab.
Rinsing out the wetting agent and the film thoroughly whilst still in the reel also helps, and is much cheaper than a water softener, which then also costs a lot of money to maintain and guzzles salt like there’s no tomorrow.
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Regards, Achim
Patrick
Hello Achim,
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Without wanting to start a general debate for and against water softeners, this system isn’t being installed for the photo lab but to protect the other appliances in a newly renovated house (water boilers, etc.), in an area where they would otherwise usually be damaged by limescale. It also has a bypass, meaning you can still water the garden with untreated water, as well as wash the car, etc.
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My question was more whether this water could have a negative effect on film and paper development due to the slightly higher sodium concentration. I’d be grateful to hear about any experiences forum members may have. Thanks in advance!
Wolfgg
Hi Patrick,
Why don’t you just carry out a test yourself? Simply develop a film strip using the original water, then one using the treated water. Make sure you use the same test shots on both film strips. That way, you’ll know the results for *your* specific circumstances much more accurately than anyone else could predict.
In principle, however, it would be better to get a reverse osmosis system from eBay or elsewhere; a three-stage one will do and costs less than 40 euros new, or much less at auction. This easily removes 99% of dissolved substances and provides optimal developing water for everything in the darkroom. When used as the final rinse water (surfactant solution), it also prevents any limescale stains from forming.
Regards, Wolfgang
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AchimBauer
Hi Patrick,
It’s good that you’ve got a Gypass for the garden.
If you’ve been getting on fine with the water so far, keep using the old one until you know that the water softener is delivering consistent results. Then expose a film with uniform motifs, split it in the middle, develop one half in the old water and the other in the new water identically, and you’ll see the difference.
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Regards, Achim
Renate
Hello,
I’ve been using demineralised water together with a wetting agent for the final rinse for quite some time now, and so far I haven’t noticed any drawbacks. The films dry completely free of spots and streaks. It saves me the hassle of having to wipe the films down.
For developing, Spur recommends distilled water. I’ve tried this with HC 110, 1+44. That worked well too. However, I haven’t carried out any denitometric tests with it yet. The problem with the water that goes through the reverse osmosis system is that the pH value drops. It then lies between 5 and 6, whereas the source water is pretty much exactly 7. However, the activity of the developer depends crucially on the pH value. I haven’t had time yet to look into this in more detail. At least with highly diluted developers, the pH value could shift unfavourably. With hard water, on the other hand, side reactions may occur which also reduce the developer’s activity.
Here we have yet another example where testing is advisable, as otherwise the results depend very much on chance.
Best regards
Renate
hallertauBW
Hello Patrick,
I’ve been using water from a water softener (Brita) for two years now. Here in Upper Bavaria, the water is very hard.
In short: I haven’t had any negative experiences. This is, of course, my subjective impression; I haven’t carried out any measurements.
Best regards,
Guido
Wolfgg
Hello Renate,
My tap water has a pH of 7.4 straight from the tap, and after reverse osmosis I measure 6.4 (I’ve just rechecked both using a glass pH strip). This must be caused by dissolved CO₂, as even small amounts are enough to significantly shift the pH value in highly pure water.
All commercial developers contain buffering agents that certainly have no problem coping with that small amount of CO2 (more precisely: the resulting weak carbonic acid). When I think back to my density curve measurements with Rodinal 1:200 stand development, I would have immediately noticed any unexplained fluctuations (from 0.1D). So, in my view: no concerns about making everything in the darkroom using reverse osmosis water, including highly diluted developers such as Rodinal 1:200.
Regards, Wolfgang
jochen53
Hello,
Many developers contain either sodium sulphite as a stabilizer (D-76, for example, contains 100 g/l!) or sodium carbonate, metaborate, tetraborate or similar compounds as an alkali. So there is sodium in them anyway. Unless the tap water is extremely hard (e.g. Würzburg with approx. 40° dH), the small amount of sodium added by the Brita filter is unlikely to have any effect on the development process. Sodium ions themselves are not chemically involved in the development process; only the anions such as carbonate, sulphite, hydroxide, etc.
Very high concentrations of sodium salts (sodium sulphate) are/were used, for example, in so-called tropical developers. There, the high salt concentration counteracts the strong swelling of the gelatin at high processing temperatures.
Incidentally, ready-made developers contain water-softening substances, so-called complexing agents, such as EDTA-Na4, HEDP or sodium polyphosphates (sodium in there again!), so distilled water is not required, but it does no harm either. When preparing your own solution, you must add these substances yourself or use distilled water.
Whilst it is true that the pH value has a decisive influence on the development kinetics, a certain buffer capacity is also required, because H+ ions lower the pH value during the reduction of AgBr.
It is also important that the water used for the solution contains as few heavy metal ions (copper, iron, etc.) as possible. These catalyse the oxidation of the developer substances and reduce their shelf life. Ready-made products also contain something to counteract this.
Hard water should be boiled before preparing developers. This breaks down part of the water hardness – the so-called temporary hardness – and causes calcium carbonate to precipitate. You let this settle and then pour off the clarified water from the top. Furthermore, boiling the water also removes the dissolved oxygen, meaning the developer does not oxidise as quickly.
So there is no need to worry excessively about the water.
Patrick
Hello, thank you very much for your interesting replies. As soon as my photo lab is up and running, I’ll carry out some tests and let you know the results. It’s good to know, however, that I don’t need to worry too much. Kind regards, Patrick.
